Analysis of the electronic structure of β-SiO2 intrinsic defects based on Density Functional Theory

Wang, Chongkun; Guo, Xiaoguang; Zhang, Shuohua; Qi, Yongnian; Gao, Shang

doi:10.1016/j.mtcomm.2023.105554

Cited by 6 publications

(1 citation statement)

References 30 publications

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“…The surface of carbon quantum dots located in CQDs/clinoptilolite composites has functional groups such as hydroxyl groups and carboxyl groups, which have the effect of inhibiting photogenerated electron recombination. The clinoptilolite is loaded with CQDs, which induce the formation of electron-hole pairs of SiO 2 in the clinoptilolite to absorb oxidants or reducing agents to generate reactive radicals and oxidize xylene gas [45]. In catalytic degradation reactions, photogenerated electrons react with O 2 in air to generate •O 2 − , while holes trap H 2 O molecule formation •OH [46].…”

Section: Mechanistic Analysis Of Photocatalytic Performancementioning

confidence: 99%

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

et al. 2023

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In this work, a series of clinoptilolite composites decorated with carbon quantum dots (CQDs/clinoptilolite) with hierarchical pore structures was demonstrated that exhibits good photocatalytic performance for the removal of xylene. The technique for the attachment of carbon quantum dots to clinoptilolite was prepared by a hydrothermal method in this study. The structural features were confirmed by SEM, TEM, EDS, XRD, BET, XPS, and solid diffuse reflection measurements, while the degradation mechanism was investigated by adding a trapping agent into the nanocomposites. The introduction of CQDs promoted the separation of photogenerated electrons and holes as well as the generation of reactive radicals, which effectively improved the light utilization and even increased the degradation rate of xylene by 73% at the optimal state. The photocatalytic test was conducted under a different dwell time, catalyst dosage, initial concentration, and illumination intensity. The results showed that the degradation rate of xylene by the CQDs/clinoptilolite catalyst reached 97.4% under the optimal reaction conditions (the catalyst was Catalyst No. 2, the residence time was 90 s, the initial concentration was 2.5 g/m3, the light intensity was three lamps for irradiation, and the catalyst dosage was 0.05 g). In addition, the degradation efficiency of the CQDs/clinoptilolite photocatalyst still reached 78% after eight consecutive catalytic regeneration cycles. This work sheds new light on the degradation of xylene.

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Section: Mechanistic Analysis Of Photocatalytic Performancementioning

confidence: 99%

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

et al. 2023

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Ab-initio study of point defects in Th and U alloy

Startt,

Deo

2024

Journal of Nuclear Materials

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First-principles study of oxygen vacancy defects in β-quartz SiO₂/Si interfaces

Zheng,

Xu,

Feng

et al. 2024

J. Phys. D: Appl. Phys.

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Understanding the electronic structures of gate oxides in Si-based devices is significant for improving device performance. We investigate the electronic properties of the oxygen vacancy defects in β-quartz SiO2/Si interface structure using first-principles calculations. The results indicate that the constructed (SiO2)4/(Si)4 structure is an indirect-gap semiconductor, with its band edges contributed by Si side and a large band-edge energy difference (> 1.780 eV). Our study reveals that the presence of oxygen vacancy defects reduces the band gap, and VO1 is transformed from indirect into direct band gap. The Si dangling bonds in VO1 cause charge localization around the O vacancy, while the formation of Si-Si bonds in VO2 and VO3 lead to electron delocalization. In the calculationof defect formation energies, we find that VO1 maintains the lowest formation energy across different states, making it more likely to form and structurally stable. Compared to O-rich environments, the formation energy in O-poor environments is overall reduced by approximately 4.5 eV, indicating that oxygen vacancy defects are more likely to form and be controlled under O-poor conditions. Ourstudy emphasizes the importance of interface structure and defect characteristics in semiconductor research, providing insights for the development of Si-based devices.

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Analysis of the electronic structure of β-SiO2 intrinsic defects based on Density Functional Theory

Cited by 6 publications

References 30 publications

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

Ab-initio study of point defects in Th and U alloy

First-principles study of oxygen vacancy defects in β-quartz SiO₂/Si interfaces

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Analysis of the electronic structure of β-SiO2 intrinsic defects based on Density Functional Theory

Cited by 6 publications

References 30 publications

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

Photocatalytic Degradation of Xylene by Carbon Quantum Dots/Clinoptilolite Composites

Ab-initio study of point defects in Th and U alloy

First-principles study of oxygen vacancy defects in β-quartz SiO2/Si interfaces

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Product

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About

First-principles study of oxygen vacancy defects in β-quartz SiO₂/Si interfaces